MC68HC08AZ32A Datasheet, PDF (173/312 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Pin Name Conventions
14.3 Pin Name Conventions
The generic names of the SCI input/output (I/O) pins are:
• RxD (receive data)
• TxD (transmit data)
SCI I/O lines are implemented by sharing parallel I/O port pins. The full name of an SCI input or output
reflects the name of the shared port pin. Table 14-1 shows the full names and the generic names of the
SCI I/O pins.
The generic pin names appear in the text of this section.
Table 14-1. Pin Name Conventions
Generic Pin Names
Full Pin Names
RxD
PTE1/RxD
TxD
PTE0/TxD
14.4 Functional Description
Figure 14-3 shows the structure of the SCI module. The SCI allows full-duplex, asynchronous, NRZ serial
communication among the MCU and remote devices, including other MCUs. The transmitter and receiver
of the SCI operate independently, although they use the same baud rate generator. During normal
operation, the CPU monitors the status of the SCI, writes the data to be transmitted, and processes
received data.
14.4.1 Data Format
The SCI uses the standard non-return-to-zero mark/space data format illustrated in Figure 14-2.
8-BIT DATA FORMAT
BIT M IN SCC1 CLEAR
PARITY
BIT
NEXT
START
START
BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 ^STOP BIT
BIT
START
9-BIT DATA FORMAT
BIT M IN SCC1 SET
PARITY
BIT
NEXT
START
BIT BIT 0 BIT 1 BIT 2 BIT 3 BIT 4 BIT 5 BIT 6 BIT 7 BIT 8 STOP BIT
BIT
Figure 14-2. SCI Data Formats
MC68HC08AZ32A Data Sheet, Rev. 2
Freescale Semiconductor
173